NEW YORK (AP) — How long does COVID-19 vaccine protection last?
Scientists are still researching vaccinated people to see when protection wears off, so they don’t know yet. The effectiveness of the vaccines against new variations will also determine whether, when, and how frequently more injections are required.
Deborah Fuller, a vaccine researcher at the University of Washington, remarked, "We only have information for as long as the vaccinations have been examined.". “We need to look into the vaccinated population and discover when people become vulnerable to the virus again.”
Pfizer’s two-dose vaccine appears to be extremely successful for at least six months, if not longer, according to the continuing experiment. Six months after the second needed shot, people who received Moderna’s vaccination still retained significant levels of virus-fighting antibodies.
Antibodies don’t give the complete story, either. Our immune systems have another line of defense called B and T cells to fight off intruders like viruses, and some of these cells can survive long after antibody levels have dwindled. If they come across the same virus again in the future, those battle-tested cells may be able to respond more quickly.
Even if they don’t completely prevent illness, they may be able to reduce its severity. But it’s unclear what role such "memory" cells might play with the coronavirus, and for how long.
While the current COVID-19 immunizations are expected to last at least a year, they are unlikely to provide lifelong protection, like measles vaccines do, according to Dr. Kathleen Neuzil of the University of Maryland School of Medicine.
“It’ll be somewhere in the middle of that extremely broad range,” she predicted.
Another reason we could require a second shot is because of variations.
According to Mehul Suthar of the Emory Vaccine Center, current vaccinations are designed to fight against a specific spike protein on the coronavirus. Vaccines may need to be updated if the virus mutates enough over time to make them more effective.
So far, the vaccinations appear to be effective against the most notable variations that have appeared, though not so much against the one discovered in South Africa.
If another shot is needed, a single dosage could extend the current vaccine’s protection or contain immunization for one or multiple variations.
The need for follow-up vaccinations will be determined in part by the efficacy of the worldwide immunization campaign and the virus’s and new variants’ spread.
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